<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .box{
        width: 45%;
        height: 30px;
        background-color: black;
        border-radius: 50px;
        margin: 0px auto;
    }
    .box:hover{
        animation: move .3s forwards;
        animation-timing-function: cubic-bezier(.666, 0, .4, 1.2);
        
    }

    @keyframes move {
        70%{
            width: 100%;
            height: 50px;
        }
        95%{
            width: 95%;
            height: 50px;
        }
        100%{
            width: 98%;
            height: 50px;
        }
    }
</style>
<body>
    <div class="father_box">
        <div class="box"></div>
    </div>
</body>
</html>

